Electrocardiogram Characteristics that Distinguish Perimitral Reentry from Other Atrial Tachycardias after Atrial Fibrillation Ablation

Introduction: Ablation of Atrial Fibrillation (AF) can induce several types of Atrial Tachycardias (ATs). Perimitral reentry is a common mechanism among postablation ATs. The electrocardiographic (ECG) criteria for differentiating perimitral reentry from other postablation ATs may be useful in clinical practice. Methods and results: A total of 48 consecutive post atrial fibrillation ablation patients with AT which occurred during ablation of recurrent atrial fibrillation were enrolled. We analyzed surface 12-lead ECG of 61 ATs. As for the patients, their doctors decided whether to stop antiarrhythmic drugs before ablation. We analyzed the ECG of the first 30 ATs in 24 patients, and developed an algorithm for differentiating perimitral reentry from other ATs based on P-wave morphology. We then prospectively evaluated this algorithm in the following 31 ATs in 24 patients. The polarity of P waves during AT were classified as positive, negative, positive/negative, negative/positive, or isoelectric in each of the 12 leads. The mechanism of 30 ATs were identified as perimitral reentry (n = 15), other macroreentry (n = 7), centrifugal AT (n = 5), gap-related left atrial and pulmonary vein reentry (n = 2), and tachycardia within reconnected PV (n = 1). P waves in perimitral reentry displayed three morphological features: 1) a positive P wave in lead V1 (sensitivity 87%), 2) isoelectric P wave in at least one precordial lead (sensitivity 93%), and 3) no negative or biphasic P wave in precordial leads (sensitivity 93%). In the prospective evaluation, an algorithm based on the above three criteria resulted in an overall accuracy of 81% in predicting whether AT was due to perimitral reentry or not. Conclusions: We report a new P-wave algorithm using only the precordial leads that helps distinguish perimitral reentry from other postablation ATs